For example, there is a temperature sensor disposed in an exhaust system of a vehicle that measures the temperature of the exhaust gas.
The temperature sensor has a built-in thermosensitive element that changes its electrical characteristics with the temperature.
A paired temperature sensor integrated by connecting two of such temperature sensors to a single connector is proposed (refer to Japanese Translation No. 2010-530540 of PCT International Application, for example).
For example, the paired temperature sensor may be used by placing a pair of the temperature sensors respectively upstream and downstream of a catalytic converter for exhaust gas purification.
Thereby, it is possible to confirm the state of deterioration of catalyst in the catalytic converter based on the difference between the values measured by the pair of the temperature sensors.
However, even though the electrical characteristics for the temperature of the pair of the temperature sensors (thermosensitive element) in the above paired sensor are exactly the same, the temperature differences between the two measured objects becomes reversed if the paired sensor is attached to the vehicle or the like in a wrong way (for example, attached to a reverse position with respect to the catalytic converter), thus the information cannot be transmitted accurately.
Further, even if the paired sensor is attached to the vehicle or the like correctly without any mistake, the temperature differences between the two measured objects becomes reversed in the same way if lead wires of the paired temperature sensor are connected to a wrong destination when connecting the paired sensor to the controller side, thus the information cannot be transmitted accurately.
Furthermore, if the electrical characteristics for the temperature of the pair of the temperature sensors (thermosensitive element) in the paired temperature sensor are significantly different, it is impossible to accurately measure the temperature differences between the two measured objects of the paired temperature sensor.
On the other hand, there is a possibility that variation occurs in the electrical characteristics with respect to the temperature in the thermosensitive element due to the manufacturing variations.
That is, it is difficult to make the electrical characteristics for the temperature exactly the same, and there is a possibility that two thermosensitive elements selected arbitrarily may output different output values for the same temperature, for example.
However, a problem arises that the temperature differences between the two measured objects cannot be measured accurately as described above if a large difference occurs between the electrical characteristics of the thermosensitive elements in the two temperature sensors that constitute a single paired temperature sensor.
Thus, for example, there is a possibility that it is not possible to accurately measure the temperature difference between the upstream side and the downstream side of the catalytic converter, and therefore accurate catalyst deterioration determination becomes difficult.
In addition, although it is conceivable to assume that the pair of the temperature sensors having the thermosensitive elements have a difference in the electrical characteristics that are below a predetermined value, in a product after inspecting the entire paired temperature sensor after manufacturing, it is impossible to increase product yield and it is difficult to obtain high production efficiency.
Further, if the lead wires are connected to wrong positions during attaching the lead wires of the paired temperature sensor to a single connector, the temperature difference between the two measured objects becomes reversed similarly, thus the information cannot be transmitted accurately.